Apparatus for observation in a high velocity liquid stream

Abstract

The invention relates to an apparatus capable of observing an object in the path of a liquid stream while a radiation receiving part of the apparatus is positioned in the liquid stream. In a preferred form the invention relates to an apparatus capable of monitoring an excavation, which uses a high velocity liquid stream as the means of excavation, while the excavation is in progess, the invention comprising radiation receiving means for observing an object when the radiation receiving means is in a clear liquid stream flowing towards the object, the radiation receiving means comprising an observation window and cavitation prevention means disposed adjacent the observation window downstream thereof, the cavitation prevention means substantially assuming the shape of a zone of cavitational probability of a downstream end of the radiation receiving means when in a liquid stream of a selected velocity at which cavitation is possible, said cavitation prevention means thereby preventing cavitation when the liquid stream passes said downstream end of the radiation receiving means at or below the selected velocity.

What I claim as my invention is: 
     
       1. An apparatus comprising radiation receiving means for observing an object when the radiation receiving means is in a clear liquid stream flowing towards the object, the radiation receiving means comprising an observation window and cavitation prevention means disposed adjacent the observation window downstream thereof, the cavitation prevention means substantially assuming the shape of a zone of cavitational probability of a downstream end of the radiation receiving means when in a liquid stream of a selected velocity at which cavitation is possible, said cavitation prevention means thereby preventing cavitation when the liquid stream passes said downstream end of the radiation receiving means at or below the selected velocity. 
     
     
       2. An apparatus according to claim 1 wherein the liquid is water and the radiation is visible light. 
     
     
       3. An apparatus comprising visible light radiation receiving means for observing an object when the radiation receiving means is in a clear water stream flowing towards the object, the radiation receiving means comprising an observation window and cavitation prevention means disposed adjacent the observation window downstream thereof, the cavitation prevention means substantially assuming the shape of a zone of cavitational probability of a downstream end of the radiation receiving means when in a water stream of a selected velocity at which cavitation is possible, said cavitation prevention means thereby preventing cavitation when the water stream passes said downstream end of the radiation receiving means at or below the selected velocity, wherein the apparatus further comprises a first conduit to guide the water stream towards the object and the radiation receiving means is located within said first conduit. 
     
     
       4. An apparatus according to claim 3 capable of generating a liquid stream of sufficient velocity to uncover an object buried in loose particulate matter. 
     
     
       5. An apparatus according to claim 3 wherein the radiation receiving means comprises a video camera for continuous viewing. 
     
     
       6. An apparatus according to claim 3 wherein ilumination means is arranged around the observation window to illuminate the object. 
     
     
       7. An apparatus according to claim 3 further comprising a valve capable of remote operation so that by manipulating a part of the water stream the location of the downstream end of the first conduit may be controlled. 
     
     
       8. An apparatus according to claim 3 further comprising manipulating means capable of remote operation for manipulating the object under observation. 
     
     
       9. An apparatus according to claim 3 wherein the cavitation prevention means encloses a compensating liquid whose refractive index is substantially the same as that of the water stream to prevent refractive distortion of the radiation reaching the radiation receiving means. 
     
     
       10. An apparatus according to claim 3 wherein the cavitation prevention means encloses a compensating liquid whose refractive index is substantially different from that of the water stream for a magnification, diminishing or wise-angle effect. 
     
     
       11. An apparatus according to claim 3 wherein the cavitation prevention means extends to a point, to enhance prevention of cavitation in a water stream of high velocity. 
     
     
       12. An apparatus according to claim 3 wherein a frusto-conical window with complementary optical elements is located in the cavitation prevention means at the downstream end thereof to allow an increased angle of view with minimal window area interfacing the water stream. 
     
     
       13. An apparatus according to claim 3 wherein the radiation receiving means is located within the first conduit such that the cavitation prevention means is adjacent the downstream end of the first conduit and the first conduit is shaped to follow the shape of the cavitation prevention means such that the water flowing past the cavitation prevention means has a cross-sectional area which is substantially uniform. 
     
     
       14. An apparatus according to claim 13 wherein a frusto-conical window with complementary optical elements is located in the cavitation prevention means at the downstream end thereof to allow an increased angle of view with minimal window area interfacing the water stream. 
     
     
       15. An apparatus according to claim 13 wherein the radiation receiving means comprises a video camera for continuous viewing. 
     
     
       16. An apparatus according to claim 13 wherein illumination means is arranged around the observation window to illuminate the object. 
     
     
       17. An apparatus according to claim 13 further comprising a valve capable of remote operation so that by manipulating a part of the water stream the location of the downstream end of the first conduit may be controlled. 
     
     
       18. An apparatus according to claim 13 further comprising gripping means capable of remote operation for gripping the object under observation. 
     
     
       19. An apparatus according to claim 13 wherein the cavitation prevention means encloses a compensating liquid whose refractive index is substantially the same as that of the water stream to prevent refractive distortion of the radiation reaching the radiation receiving means. 
     
     
       20. An apparatus according to claim 13 wherein the cavitation prevention means encloses a compensating liquid whose refractive index is substantially different from that of the water stream for a magnification, diminishing or wide-angle effect. 
     
     
       21. An apparatus according to claim 13 wherein the cavitation prevention means extends to a point, to enhance prevention of cavitation in a water stream of high velocity. 
     
     
       22. An apparatus according to claim 13 wherein a frusto-conical objective lens is located in the cavitation prevention means at the downstream end thereof to increase the angle of view. 
     
     
       23. An apparatus according to claim 13 wherein the downstream end of the first conduit is convergent to increase the back-pressure within the apparatus and discharge velocity of the water stream. 
     
     
       24. An apparatus according to claim 13 wherein the downstream end of the first conduit is divergent to reduce back-pressure within the apparatus and velocity of the discharged water stream. 
     
     
       25. An apparatus according to claim 13 wherein the first conduit is disposed within a second conduit, the second conduit being adapted to transport debris or particulate matter away from the radiation receiving means. 
     
     
       26. An apparatus according to claim 25 wherein the first conduit is adapted so that a portion of the liquid stream passing through the first conduit is caused to flow in a reverse direction in the second conduit. 
     
     
       27. An apparatus according to claim 25 further comprising processing means for processing debris or particulate matter transported by the second conduit. 
     
     
       28. An apparatus according to claim 25 where the display means may be disposed adjacent to or remote from the radiation receiving means.